The invention relates generally to a method for detecting toxic chemical concentration in an individual and, more particularly, to such a method employing electromyographic (EMG) signals as a detection mechanism.
There are a number of agents used for chemical warfare including Nerve Agents, Toxins, Blister Agents, Blood Agents, and Incapacitating Agents. Of these the most threatening are the Nerve Agents [Soman (GD), Sarin (GB), Four-Amino Pyridine (4-AP), Tabun (GA), and VX] and the Neuro Toxins [Saxitoxin (STX) and Tetrodotoxin (TTX)]. The world-wide military community addresses these threats with environmental alarms, protective clothing, and medical responses. The sensitivity of field alarms and the life-cycle of protective clothing are limited, however, so individual exposures are to be expected. Similarly, exposures in the civilian population may be expected in the agriculture, insecticide, manufacturing, fire fighting, hazmat transportation, and police communities.
The effects of exposure will depend upon the type of chemical, concentration, length of exposure, and method of exposure (skin, wound, mouth, lung, eye). If high concentrations appear in the blood stream, the effect may be lethal and a medical response within minutes may be required. If low concentrations appear in the blood stream, then natural recovery without medical attention may be possible.
Low level exposures cannot be ignored since the effects are cumulative and multiple exposures may result in a casualty. Immediate evacuation after the first exposure is crucial, but the problem is to identify individuals who have been exposed if the concentrations are too low to be detected by existing field alarms. Two methods currently employed are blood tests and observation of physiological symptoms. Blood testing such as for reduced levels of actylcholinesterase is accurate but impractical due to the length of time required for analysis and due to the large numbers of false alarms that will also draw blood. As a result, reliance world-wide is based upon subjective visual observations.
The physiological symptoms of exposure vary with the chemical agent and concentration. These can include: headache, slurred speech, fatigue, nausea, hallucination, runny nose, impaired night vision, degraded short range vision, pinpointing of the eyes, tightness of the chest, excessive sweating and salivating, excessive urination and defecation, muscle spasms, weakness, convulsion, respiratory and cardiac failure. For low-level exposures the effects are reduced and the symptoms may be ignored or go unrecognized.
The object of this invention, therefore, is to provide an improved method for detecting the presence of toxic biological-chemicals in individuals having been exposed to such agents.